The use of gas-insulated high-voltage equipment for electrical transmission purposes is quite old. Reference may be made, for example, to U.S. Pat. No. 3,856,978, issued Dec. 24, 1974 to Andreas M. Sletten and Alan H. Cookson, and assigned to the Westinghouse Electric Corporation. In this patent are set forth certain prior-art background patents relating to high-voltage component parts utilized in gas-insulated equipment. The advantages of such gas-insulated equipment are set forth in the following U.S. Pat. Nos.: 3,700,840 -- Wilson et al; 3,694,592 -- Kuhn; 3,610,807 -- Whitehead; Canadian Pat. No. 904,412 -- Trump; U.S. Pat. No. 3,348,001 -- Upton et al; and U.S. Pat. No. 3,378,731 -- Whitehead.